3. Why is breathing clean air so important for heart health?

Fossils can only be formed when? if mud, silt or tar is in the area to preserve the fossil ierosion does not occur and allows the fossil to form oxygen and microorganisms cannot decay the bones the area is dry and does not contain mud or silt

As a small change in a person's dna can cause a genetic disorder

Which is one example of a phenotypic change that is not genetic